Chain belt power transmission

ABSTRACT

A power transmission (10) chain-belt (32) is disclosed that is especially aptable for connecting the pulleys (12, 14) of a pulley transmission (10). The chain-belt (32) has a plurality of interleaved sets (34) of links (36and each set (34) has a plurality of transversely arranged links (36). Pivot means (40) join adjacent sets (34) of links (36) to form an endless loop. At least one toe (42A, 42B) extends from each link (36) in at least some sets (34) of links. At least the toes (42A, 42) on adjacent links (36) are in opposed relationship and define a passageway (80). A plurality of load blocks (50) are connected to the links (36). The load blocks (50) are positioned in the passageway (80) defined by the toes (42A, 42B). Each load block (50) has edge surfaces (88) for connecting the pulleys (12, 14 ) of the transmission (10). A notch (90) is positioned on each side of the load blocks (50) on the surface of the load blocks (50) that is adjacent the links (36). A retaining link (92) is positioned on each side of the sets (34) of links (36). The retaining links (92) engage the notches (90) and restrain the retaining links (92) from transverse movement and assist in holding the sets (34) of links (36) together.

TECHNICAL FIELD

This invention relates to metal chain-belts especially adapted toconnect the pulleys of a pulley transmission, particularly acontinuously variable transmission (CVT), and broadly comprises atension member or carrier constructed of a plurality of interlaced linksarranged in transverse sets with the adjacent sets joined by pivotmeans, and load blocks carried by the carrier for engaging the pulleys.

BACKGROUND ART

Variable pulley transmissions for transferring torque from an input ordrive shaft to an output or driven shaft have been used for some time.In these transmissions, a first pulley constructed of a pair of flanges,at least one of which is conical, is mounted on the input shaft suchthat at least one of its flanges is axially movable with respect to itsother flange. A second, similarly constructed and adjustable pulley ismounted on the output shaft. A flexible belt connects the two pulleys totransfer torque therebetween when the input shaft is driven. As theeffective diameter of one pulley is changed, the effective diameter ofthe other pulley is changed in the other direction and, the drive ratiobetween the input and output shafts is adjusted in a smooth, continuousmanner.

Automotive engineers have long recognized that the maximum operatingefficiency of the engine could be achieved if the transmission could becontrolled by adjusting to different loads and speed ratios, such thatthe engine is maintained and operated at its maximum efficiencyoperating conditions. This has not been possible when a conventionalgeared transmission is teamed with an engine. In the conventional gearedtransmission, the drive ratio is adjusted in discrete steps, rather thancontinuously. Accordingly, efforts have been directed to the use of acontinuously varible transmission (CVT) of the type described above. Theefforts have resulted in the production and marketing in Europe of theDAF passenger car, using flexible, continuous rubber belt to drivinglyinterconnect the pulleys. Rubber belts have been considered to beinferior to metal belts because of various adverse conditions underwhich they must operate. More recently, Fiat and Volvo have producedautomobiles incorporating CVT's using respectively, metal belts andrubber belts. Some of the efforts to produce metal belts which aredurable, relatively quiet in operation, and also economical to market,are described in the patent and other literature.

Flexible metal belts for use in CVT's are generally of two varieties,those referred to as "push" belts and those referred to as "pull" belts.Push belts are currently being used in the Fiat automobile's CVT. Anexample of a push belt is described in Van Doorne et al., U.S. Pat. No.3,720,113 and an example of a pull belt is described in Cole, Jr., etal., U.S. Pat. No. 4,313,730. The Van Doorne et al. belt comprises anendless carrier constructed of a plurality of nested metal bands and anendless array of generally trapezoidal (when viewed from the front) loadblocks encircling the carrier and longitudinally movable therealong.Each block has edge surfaces engaging the pulley's flanges of a pulleytransmission to transmit torque between the pulleys. The pull belt ofCole, Jr. et al., utilizes an endless chain as the carrier, the sets oflinks of which are pivotably interconnected by pivot means. Load blocks,similar to those of Van Doorne et al., encircle the links; however, theload blocks are contrained against longitudinal movement along the chainby the pivot means.

Another example of a pull belt is shown in Ledvina, U.S. Pat. No.4,569,671 which utilizes a chain-belt comprising a plurality ofinterleaved sets of links and load blocks associated therewith. Eachlink is defined by toes, the toes of each link being defined by parallelinside flanks joined by a crotch. A load block is received between theinside flanks and extends around the links. A hardened insert is locatedbetween the links and the blocks to protect the links and improve thedurability of the chain.

The push belt as described above is relatively expensive to manufactureand must be installed and/or replaced as a complete endless loop. Thus,disassembly of at least part of the pulley transmission is required, notonly for the initial assembly, but also for replacement of the push beltdue to failure of one or more load blocks or one or more of the carrierbands.

The pull belt offers a less expensive alternative to the push belt. Noprecise matching of carrier parts is required. The belt can be assembledwith a finite length, positioned around the pulleys, and the ends thenconnected by a pivot member. Thus disassembly of the pulleys is notrequired in either for initial installation or replacement of a belt.

DISCLOSURE OF THE INVENTION

A power transmission (10) chain-belt (32) is disclosed that isespecially adaptable for connecting the pulleys (12, 14) of a pulleytransmission (10). The chain-belt (32) has a plurality of interleavedsets (34) of links (36) and each set (34) has a plurality oftransversely arranged links (36). Pivot means (40) join adjacent sets(34) of links (36) to form an endless loop. At least one toe (42A, 42B)extends from each link (36) in at least some sets (34) of links. Atleast the toes (42A, 42B) on adjacent links (36) are in opposedrelationship and define a passageway (80). A plurality of load blocks(50) are connected to the links (36). The load blocks (50) arepositioned in the passageway (80) defined by the toes (42A, 42B). Eachload block (50) has edge surfaces (88) for connecting the pulleys (12,14) of the transmission (10). A notch (90) is positioned on each side ofthe load blocks (50) on the surface of the load blocks (50) that isadjacent the links (36). A retaining link (92) is positioned on eachside of the sets (34) of links (36). The retaining links (92) engage thenotches (90) and restrain the retaining links (92) from transversemovement and assist in holding the sets (34) of links (36) together.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a continuously variabletransmission (CVT).

FIG. 2 is a schematic illustration of a continuously variabletransmission.

FIG. 3 is a side view of the chain-belt of the present invention.

FIG. 4 is a cross-sectional view taken along line 4--4 in FIG. 3.

FIG. 5 is a plan view of the chain-belt.

FIG. 6 is an exploded perspective view showing the components of thechain-belt of the present invention.

FIG. 7 is a side elevation view of another embodiment of the presentinvention.

FIG. 8 is a side elevational view of another embodiment of the presentinvention.

FIG. 9 is a cross-sectional view taken along line 9--9 in FIG. 8.

FIG. 10 is a top view of the embodiment of FIG. 8.

FIG. 11 is an exploded perspective view showing the components of thisembodiment.

FIG. 12 is an exploded perspective view showing the components foranother embodiment of the present invention.

FIG. 13 is a side elevation view of another embodiment of the invention.

FIG. 14 is a plan view of a component of the embodiment of FIG. 13.

FIG. 15 is a side elevation view of the component of FIG. 14.

FIG. 16 is a plan view of this embodiment of the invention.

FIG. 17 is an exploded perspective view showing the components of theembodiment of FIG. 13 of the invention.

FIG. 18 is a partial side elevation view of a portion of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2 illustrate schematically a CVT 10 in two drive ratios. CVT10 comprises a pair of pulleys 12 and 14 connected respectively toshafts 16 and 18, one of which is the driven shaft and the other ofwhich is the drive shaft. Pulley 12 comprises a pair of flanges 20, 22,at least one of which is conical, and pulley 14 comprises a pair offlanges 24, 26, at least one of which is conical. The pulleys areconnected by a belt 28, the side edges 30 of which frictionally engagethe pulley flanges. At least one flange of each pulley is axiallymovable with respect to the other, so as to vary the drive ratiosbetween the pulleys. The arrows indicate the axial movement of theflanges to effect the different drive ratios. Means-beyond the scope ofthis invention-can be provided for axially moving at least one flangerelative to the other.

The chain-belt 32 of this invention (see FIGS. 3 and 4 showing segmentsof the chain-belt 32) comprises a plurality of interleaved or laced sets34 of links 36, each link having a pair of spaced apertures 38, 39. Theapertures are arranged so that pivot means 40 join adjacent sets oflinks to thus permit the chain-belt to articulate. Pivot means 40 areshown as being of the pin and rocker variety but any known type of pivotmeans may be used. Because of the lacing, alternate sets of links have adifferent number of links than the other sets of links.

Each link has a pair of toes 42A, 42B, which are defined by outsideflanks 44A, 44B, and inside flanks 46A, 46B. The toes 42A, 42B aredisposed to extend from the links in a direction towards the shafts 16,18 of the CVT when the chain-belt is properly positioned on the CVT. Theinside flanks are in spaced apart, generally opposed relationship. Theinside flanks have an arcuate shape and are joined together by a curvedcrotch 48. The configuration of the inside flanks and the curved crotch48 result in the opposed toes forming a substantially circularpassageway 80 with the ends of the toes that are spaced apart from thepivot pins defining an opening 82.

A load block 50 is associated with each set of links and is received inthe passageway 80 formed by the opposed toes. The upper region 84 of theload blocks has the same basic shape as the passageway 80 and is onlyslightly smaller in size to allow the load blocks to be positioned inthe passageway. The load blocks have a lower portion 86 that extendsfrom the passageway and has ends 88 that are designed to engage theflanges of the pulleys of the CVT 10. The load blocks are preferably asolid metal block that provide a great deal of strength and resistanceto wear as the CVT operates. However, it should be understood that theload blocks can be made from more than one piece of solid metal.

The load blocks 50 have a groove or notch 90 at each end. The notch islocated in the upper region 84 of the load block that faces thepassageway 80. The chain-belt has a retaining link 92 that is positionedas the outer link on each side of the chain-belt. The retaining links 92have a projection 94 which extends into the passageway 80 defined by theopposed toes. The projection 94 is disposed to engage the notch 90 onthe load blocks to restrain the load blocks 50 from movement in adirection transverse to the direction of travel of the chain-belt 32. Inthis configuration the notches 90 also act to assist in holding thelinks 36 together as the notches also keep the links from separatingfrom one another.

When the chain-belt is in operation the upper region of the load blocks50 is pushed into contact with the curved crotch 48 area of the linkswhen the chain-belt contacts the pulleys 12 and 14 of the CVT 10. Thecurved crotch is a very strong section of the link and is very effectivein handling the load placed on the load blocks 50. The forcesencountered by the load blocks 50 are effectively distributed across thewidth of the links 36 and directed to the portion of the links where thelinks are very strong. The toes 42A and 42B do not receive much of theforces placed on the load blocks 50 by the pulleys of the CVT 10.

The flanges of the pulleys of the CVT 10 place essentially two types ofloads on the load blocks 50. The forces acting on the load blocks areshown in FIG. 18. The primary load or force on the load blocks is in aradial direction that is generally perpendicular to the direction oftravel of the chain-belt. The radial force, shown as arrow 51, acts topush the load blocks 50 in a direction toward the crotch 48 of the links36. There is also a smaller force acting on the load blocks 50 that issubstantially in the tangential direction or same direction as thedirection of travel of the chain-belt 32. The tangential forces areshown as arrow 53 in FIG. 18. The resultant force vector, shown as arrow55, that results from the combination of the large radial force 51 andthe smaller tangential force 53 always acts between points of contact 47in the crotch area 48 of the links 36 as shown in FIGS. 3 and 18. Thecrotch 48 is also constructed so that the crotch area contacts each sideof the load blocks 50 at points of contact 47. These points of contacton each side of the load blocks 50 act to stabilize the load blocks andacts to substantially eliminate rotation of the load blocks during useof the chain-belt 32. As noted above, the contact areas in the crotch 48of the links 36 at points of contact 47 are disposed so that theresultant force vector that acts on the load blocks is always betweenthe points of contact 47. Accordingly, the load blocks 50 are alwayscontacted on each side by the contact area of the crotch 48 and thissubstantially eliminates any tendency of the load blocks 50 to rotate.Most of the forces acting on the load blocks 50 are transferred to thecrotch area 48 of the links 36 and very little force is directed to thetoes 42A and 42B of the links.

Although each link 36 has been described as having a pair of toes itshould be recognized that it is only necessary that the toes form apassageway 80 for receiving the load blocks 50. It is possible for eachlink to have only one toe with the toes on adjacent links being disposedin opposed relationship to form the passageway for the load blocks 50.It is also not necessary that the toes form a substantially circularpassageway 80. The toes can have different shapes as long as thepassageway formed by the toes is capable of receiving the load blocks 50and maintaining the load blocks in position adjacent the links 36. Theportion of the load blocks 50 located in the passageways shouldpreferably be shaped to transfer forces from the CVT 10 in the mannerpreviously described.

The above construction allows the chain-belt 32 to be substantially aswide as the load blocks 50, resulting in a higher tensile capacity forthis chain-belt. On prior chain-belts, the chain-belt often passedthrough a window or opening in the load blocks and the chain had to benarrower than the load blocks. This effectively reduced the maximum sizeof the chain and reduced the maximum load carrying capacity for thechain. By suspending the load blocks 50 below the chain-belt 32, thechain-belt can be wider. This allows more or heavier links to be usedfor the chain-belt to improve the load carrying capacity of thechain-belt. Since the load blocks 50 are positioned below the chain-belt32 this increase in width can be accomplished without increasing theeffective width of the chain-belt that is contacting the pulleys 12 and14 of the CVT 10. In practice it has been found that the chain-belt 32of the present invention has approximately 55% more tensile capacitythan the above described prior art chain that is used in a CVT.

The load blocks 50 of the present invention are preferably monolithicblocks that drive directly against the links of the chain-belt 32. Themonolithic load blocks 50 are stronger than the prior art load blocksthat were formed from several plates that were positioned in adjacentrelationship to form a load block. These prior art load blocks alsocontained a window or opening and the chain-belt was positioned in theopening. The present load blocks preferably are a solid piece and do nothave an opening or window extending through the load block. These loadblocks 50 are considerably stronger than the prior art load blocks andmore readily accept the high loads and difficult operating conditionsthat exist in a CVT. The outside edges 60 of the load blocks are shapedto engage the flanges of the pulleys 12 and 14 of the CVT 10. It isrelatively easy to create a uniform outside surface 60 for contactingthe pulleys when the load block is a solid metal load block. If theplates of some of the prior art load blocks varied slightly in size orwere positioned differently around the chain-belt, slight variationscould be present on the outside edges that were disposed to contact thepulleys of the CVT. Such variations can result in an uneven outsidesurface for the load block. In this situation not all of the plates thatform the load block may be contacted by the pulleys of the CVT. Whenthis occurs there is uneven load sharing between the plates that formthe load block and the load block is less effective in transferringtorque between the pulleys and in resisting wear during use of the CVT.The solid, monolithic blocks of the present invention eliminate theabove deficiency of some of the prior art load blocks.

The load blocks 50 of the present invention are easy to position on thechain-belt 32. The load blocks are positioned in the passageway 80formed by the opposed toes 42A and 42B that extend from each link 36 ofthe chain-belt. It is easy to position the load blocks in the passageway80 and then use the retaining links 92 to secure the load blocks frommovement in the passageway. This is a much easier construction methodthan prior art load blocks that required the chain-belt to be positionedin an opening in the load block. The load blocks were then held in placeby the pins that secured adjacent sets of links together. This prior artsystem essentially required the load blocks to be positioned on thechain-belt during the formation of the chain-belt. Such a structure ismore difficult and expensive to utilize than the load blocks of thepresent invention. Accordingly, the present invention provides achain-belt for a CVT that is much cheaper and easier to assemble thanmany prior art chain-belts.

The load blocks 50 of the present invention drive directly against thelinks of the chain-belt. The load placed upon the load blocks 50 by thepulleys of the CVT is transferred to the crotch area 48 of the links 36.This load is spread across the entire width of the chain-belt 32. Thisis a very effective way to transfer the force from the load block 50 tothe chain-belt 32. In many prior chain-belts the load blocks were heldin place on the chain-belt by the pivot pins that joined the adjacentsets of links to form the chain-belt or by tabs on the links. Thesesystems resulted in very high loads on a small portion of the pins orlinks and the load blocks. Such high loads frequently limited the forcesthat could be effectively handled by such a chain-belt construction. Thepresent invention provides a system for transferring the forces from theload blocks 50 to the chain-belt 32 which significantly improves theload carrying capacity of the chain-belt.

FIG. 7 shows another embodiment of the invention wherein each toe 42A,42B, has a projection 96 that extends into the passageway 80. A groove98 is located on each side of the load blocks 50. The grooves 98 aredisposed to be in alignment with the projections 96 located on the toes.When the load blocks 50 are positioned on the chain-belt 32 theprojections 96 extend into grooves 98 and act to retain the load blocks50 in position adjacent to the links 36 of the chain-belt.

FIGS. 8, 9, 10 and 11 show another embodiment that can be used torestrain the load blocks 50 from transverse movement on the chain belt32. In this embodiment a plurality of retainer brackets 101 are used tosecure the load blocks 50 to the chain belt. The retainer brackets 101are positioned on each set 34 of links 36 and have a first section 103that extends across the side of the links 36 that is in spaced apart,opposed relationship to the passageway 80. A second section 105 of theretainer bracket extends along the sides of the links. The secondsection 105 terminates in a foot 109 and the foot extends under thepivot means 40. The pivot means secures each end of the retainer bracket101 to the chain-belt 32. The retainer bracket also extends over atleast a portion of the ends of the load blocks 50 to retain the loadblocks from movement transverse to the direction of travel of thechain-belt. The notch 91 on the ends of the load blocks 50 can bedisposed to receive the foot 109 on the second section 105 of theretainer bracket 101. As shown in FIGS. 9 and 10 the notch 91 can bepositioned at the very end of the load blocks 50. The notches 91 on theends of the load blocks 50 can be made slightly larger than thethickness of the foot 109 on the retainer bracket 101. This constructionfor the notches 91 allows the load blocks 50 to move slightly in atransverse direction in the passageways 80 to allow the load blocks 50to be aligned as the load blocks 50 pass through the pulleys of the CVT10. However, the retainer brackets 101 still function to keep the loadblocks 50 in the passageways 80 formed by the links 36.

The retainer bracket 101 can have second sections 105 that aresymetrical or the second sections can be asymetrical. In practice it hasbeen found to be preferably to have the second sections be asymetricalas shown in FIGS. 8 and 11. With an asymetrical configuration a foot 109on each side of the retainer bracket 101 extends in opposite directionsand each foot 109 engages a pivot means 40 located at one end of thesets of links 36. In this manner the retainer bracket 101 is held by thepivot means 40 associated with one set of links and there is no relativemotion between the pivot means and the retainer bracket. The foot 109 oneach end of the retainer bracket can have a grooved section 111 that isdisposed to be in alignment with the pivot means 40. The grooved section111 allows the pivot means to rotate without causing substantialmovement in the retainer bracket. The second section 105 is alsoconstructed so that there is a clearance with the pivot means 40 so thatrotation of the pivot means 40 does not cause the retainer bracket 101to move.

A recess 115 can also be positioned on the second section 105 of theretainer bracket 101 in opposed relationship to the foot 109. The recess115 is disposed to receive the foot 109 on the adjacent retainer bracket101. This allows adjacent retainer brackets to nest together to take upless space and to have less possible interference as the chain-beltarticulates.

The first section 103 of the retainer bracket can also be curved in amanner to deflect towards the links 36. When the retainer bracket 101 ispositioned on the links 36 the first section is displaced by the linksand acts like a spring. Accordingly, the first section 103 acts to pullthe second section 105 in a direction away from the load blocks 50. Asthe foot 109 is positioned under the pivot means 40 the spring action ofthe first section 103 acts to keep the foot 109 on each side of theretainer bracket 101 in contact with the pivot means 40. The springaction of the first section 103 thereby assists in maintaining theretainer bracket 101 in position on the chain-belt.

The embodiment shown in FIGS. 8-11 functions basically in the samemanner as the previously described chain-belt and has the sameadvantages of the previously described chain-belt. In addition, it isvery easy to position the load blocks 50 in the passageway 80. After thesets of links 36 have been completely assembled, the load blocks 50 canbe positioned in the passageway 80 and the retainer brackets 101positioned on the chain-belt to hold the load blocks 50 in position inthe passageway 80.

FIG. 12 shows another embodiment of the invention where the load blocks50 have a notch 91 that is located on each end of the load block 50. Thenotches 91 are cut into the very end of the load blocks 50. A guide link121 is positioned as the outer link on each side of the chain-belt 32.The guide links 121 extend into the notches 91. Ends of selected ones ofthe pin pivot means 40 are fit into end openings 93 of the guide links121. The guide links 121 act to restrain the load blocks 50 frommovement in a direction transverse to the direction of travel of thechain-belt 32. The guide links 121 also act to retain the load blocks 50in the passageway 80 formed by the toes on the links 36. The notches 91can be made slightly larger than the thickness of the guide links 121 toallow slight transverse movement of the load blocks. This slighttransverse movement of the load blocks allows the load blocks to bealigned as the load blocks 50 pass through the pulleys of the CVT 10.The slight transverse movement of the load blocks also reduces wearbetween the load blocks 50 and the guide links 121.

FIGS. 13-17 show another embodiment of the invention where a spring link131 is positioned in the previously described chain-belt 32. The springlink 131 has toes 132A and 132B and forms a channel 134 for the loadbocks 50. One spring link 131 is positioned in each set of links 36 ofthe chain belt. The channel 134 of the spring link is in substantialalignment with the passageway 80 formed by the other links 36 of thechain-belt 32 for receiving the load blocks 50. However, the channel 134of the spring link 131 is slightly smaller than the passageway 80 andthe load block 50 is press fit into the channel 134 so that the loadblock is secured to the spring link 131. The spring link 131 therebyacts to hold the load block from being displaced in a transversedirection from the passageway 80. The spring link 131 has asubstantially sine wave shape when viewed from the top of the chain-beltas shown in FIG. 14. The sine wave shape allows the spring link 131 toflex or bend in a transverse direction to accomodate small transversemovement of the load blocks 50. This small transverse movement keeps theload blocks 50 from moving relative to the spring link 131 and maintainsthe press fit between the load block 50 and the spring link 131. Withoutthe ability of the spring link 131 to move with the load block 50 thepress fit would be loosened as the load blocks 50 were aligned as theload blocks 50 move through the pulleys of the CVT 10. The use of thespring link 131 allows the grooves or notches to be eliminated from theload blocks 50. The retaining links 133 on each side of the chain-belt32 that hold the links of the chain-belt together have a groove 135 thatfits over the top of the load block 50. The use of the spring link 131eliminates possible wear problems between the retaining links and thenotches in the load blocks. This construction for the chain-belt alsoallows the load blocks 50 to be inserted into the passageway 80 as asecondary operation after the links 36 of the chain-belt have beenassembled. This simplifies and reduces the cost of assembling thechain-belt. Although only one spring link 131 has been shown in each set34 of links 36, it should be understood that more than one spring linkcan be used if desired and that different positions in the set of linkscan be utilized for the spring links.

The above description is given for the sake of explanation. Varioussubstitutions and modifications, other than those cited, can be madewithout departing from the scope of the following claims.

I claim:
 1. A power transmission (10) chain-belt (32) especiallyadaptable for connecting the pulleys (12, 14) of a pulley transmission(10) comprising:a plurality of interleaved sets (34) of links (36), eachset (34) having a plurality of transversely arranged links (36); pivotmeans (40) joining said adjacent sets (34) of links (36) to form anendless loop; a passageway (80) defined by said sets (34) of links (36);a plurality of load blocks (50) connected to said links (36), a portionof said load blocks (50) being positioned in said passageways (80), saidpassageway (80) partially enclosing said load block (50) wherein asection of said load block (50) extends radially from said passageway ina direction toward the center of said pulley, each load block (50)having edge surfaces (88) for contacting said pulleys (12, 14) of saidtransmission (10); at least one notch (90) positioned on each end ofsaid load blocks (50), said notches (90) being positioned on the surfaceof said load blocks (50) that is adjacent said links (36); a retaininglink (92) being positioned on each side of said sets (34) of links (36),said retaining links (92) engaging said notches (90) whereby saidretaining links (92) restrain said load blocks (50) from transversemovement and said notches (90) position said retaining links (92) toassist in holding said set (34) of links (36) together.
 2. Thechain-belt (32) of claim 1, wherein at least one toe (42A, 42B) extendsfrom each link (36) in at least some sets (34) of links (36), at leastsaid toes (42A, 42B) on adjacent links (36) being in opposedrelationship and said toes (42A, 42B) define said passageway (80), saidportion of said opposed toes (42A, 42B) that form said passageway (80)have an arcuate shape and said toes (42A, 42B) form a substantiallycircular passageway (80) with the ends of said opposed toes (42A, 42B)that are spaced apart from said pivot means (40) defining an opening(82).
 3. The chain-belt (32) of claim 1, wherein said load blocks (50)are solid metal blocks that extend substantially across the width ofsaid interleaved sets (34) of links (36).
 4. The chain-belt (32) ofclaim 3, wherein said load blocks (50) have a region (84) forpositioning in said passageway (80), said region (84) of said loadblocks (50) having substantially the same shape and size as saidpassageway (80), said passageway (80) having a shape to retain said loadblocks (50) in position adjacent said links (36).
 5. The chain-belt (32)of claim 1, wherein said retaining links (92) have a projection (94)that extends from said retaining links (92) to engage said notches (90).6. The chain-belt (32) of claim 3, wherein said load blocks (50) haveuniform edge surfaces (88) for contacting said pulleys (12, 14) wherebysaid edge surfaces (88) uniformly transfer the load from said pulleys(12, 14) to said links (36).
 7. The chain-belt of claim 1, wherein eachlink (36) has only one toe (42A, 42B) and the toes (42A, 42B) onadjacent links being disposed in opposed relationship to form saidpassageway (30).
 8. A power transmission (10) chain-belt (32) especiallyadaptable for connecting the pulleys (12, 14) of a pulley transmission(10) comprising:a plurality of interleaved sets (34) of links (36), eachset (34) having a plurality of transversely arranged links (36); pivotmeans (40) joining said adjacent sets (34) of links (36) to form anendless loop; at least one toe (42A, 42B) extending from each link (36)in at least some sets (34) of links (36), at least said toes (42A, 42B)on adjacent links (36) being in opposed relationship and said toes (42A,42B) defining a passageway (80), said portion of said opposed toes (42A,42B) that form said passageway (80) having an arcuate shape and saidtoes (42A, 42B) forming a substantially circular passageway (80) withthe ends of said opposed toes (42A, 42B) that are spaced apart from saidpivot means (40) defining an opening (82); a plurality of load blocks(50) connected to said links (36), a portion of said load blocks (50)being positioned in said passageways (80) defined by said toes (42A,42B), said portion of said load blocks (50) having a shape conformingsubstantially to the shape of said passageway (80), said passageway (80)partially enclosing said load block (50) wherein a section of said loadblock (50) extends radially from said opening (82) defined by saidopposed toes (42A, 42B) in a direction towards the center of saidpulleys, each load block (50) having edge surfaces (88) for contactingsaid pulleys (12, 14) of said transmission (10); a notch (90) positionedon each end of said load blocks (50), said notch (90) being positionedon the upper region (84) of said load blocks (50) that is adjacent saidlinks (36) and that faces said passageway (80); and a retaining link(92) being positioned on each side of said sets (34) of links (36), saidretaining links (92) engaging said notches (90) whereby said retaininglinks (92) restrain said load blocks (50) from transverse movement andsaid notches (90) position said retaining links (92) to assist inholding said set (34) of links (36) together.
 9. The chain-belt (32) ofclaim 8, wherein said load blocks (50) are solid metal blocks thatextend substantially across the width of said interleaved sets (34) oflinks (36).
 10. The chain-belt (32) of claim 8, wherein said load blocks(50) have a region (84) for positioning in said passageway (80) formedby said opposed toes (42A, 42B), said region (84) of said load blocks(50) having substantially the same shape and size as said passageway(80), said passageway (80) having a shape to retain said load blocks(50) in position adjacent said links (36).
 11. The chain-belt (32) ofclaim 8, wherein said retaining links (92) have a projection (94) thatextends from said retaining links (92) to engage said notches (90). 12.The chain-belt (32) of claim 9, wherein said load blocks (50) haveuniform edge surfaces (88) for contacting said pulleys (12, 14) wherebysaid edge surfaces (88) uniformly transfer the load from said pulleys(12, 14) to said links (36).